High-flow, high-pressure inline saturator system and method thereof

ABSTRACT

There is provided an inline saturator system and method for gas exchange with an aqueous-phase liquid. The system includes a pressure vessel, configured to receive a first liquid and a first gas from external sources and to discharge a second liquid and a second gas from the pressure vessel, and a gas infusion device situated within the pressure vessel. The gas infusion device is configured to receive the first liquid and first gas, to facilitate gas exchange therebetween, producing the second liquid and the second gas, and to discharge the second liquid and second gas into the pressure vessel. The system further includes a recirculation system configured to direct a portion of liquid within the pressure vessel back into the saturator device, where injection of the redirected liquid into the gas infusion device forces the first liquid into the gas infusion device for the gas exchange.

TECHNICAL FIELD

The invention relates generally to systems and a method that dissolvegas into a liquid and, more particularly, to inline saturator systemsfor use in aquaculture.

BACKGROUND

Whether dealing with fish, shell fish, or crustaceans in the aquacultureand wild fisheries industry, it is critical to be able to control thedissolved gas environment in the associated water. In general, there aretwo issues that must be controlled: maintaining sufficient dissolvedoxygen for respiration, and removing the dissolved carbon dioxideresulting from respiration.

It is generally understood that higher levels of dissolved oxygen in thewater have a positive influence on the health and growth rate of fish.Within the aquaculture industry, the usual approach to maintainingdissolved oxygen levels involves the injection of oxygen gas through oneor more high-pressure venturi nozzles.

While this approach is viable, it also increases the total gas pressure,which in turn, tends to cause the oxygen to bubble out of the water. Itis also known that the overall dissolved gas pressure can play asignificant role in fish health and growth rate, etc. As such, a furtherissue concerns the fact that prolonged exposure to an elevated total gaspressure can be a health hazard to the biomass in the water.

SUMMARY

This disclosure provides an inline saturator system for gas exchangewith an aqueous-phase liquid, the system comprising:

a pressure vessel configured to receive a first liquid and a first gasfrom external sources, and to discharge a second liquid and a second gasfrom the pressure vessel;

a gas infusion device situated within the pressure vessel, the gasinfusion device configured to receive the first liquid and first gas, tofacilitate gas exchange between the first liquid and first gas,producing the second liquid and the second gas, and to discharge thesecond liquid and second gas into the pressure vessel; and

a recirculation system configured to redirect a portion of liquid withinthe pressure vessel back into the saturator device;

wherein injection of the redirected liquid into the gas infusion deviceforces the first liquid into the gas infusion device for the gasexchange.

This disclosure also provides a method for gas exchange with anaqueous-phase liquid, the method comprising:

injecting a first liquid and a first gas into a pressure vessel;

directing the first liquid and the first gas through a gas infusiondevice situated within the pressure vessel, the gas infusion deviceconfigured to facilitate gas exchange between the first liquid and thefirst gas, producing a second liquid and a second gas;

redirecting a portion of the second liquid back into the saturatordevice; and

discharging the remaining second liquid out of the pressure vessel;

wherein the redirection of the second liquid into the gas infusiondevice draws the first liquid into the gas infusion device for the gasexchange.

Advantages and features of the invention will become evident upon areview of the following detailed description and the appended drawings,the latter being briefly described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference will now be made, by way of example, to the accompanyingdrawings which show an example of the present application, in which:

FIG. 1 is a plan view of a saturator system according to an example ofthe present invention with access doors in the open position;

FIG. 2 is a front view of the saturator system of FIG. 1 with theinternal components shown in dashed lines and the access doors in theclosed position;

FIG. 3 is a right side view of the saturator system of FIG. 2 with theinternal components shown in dashed lines;

FIG. 4 is a schematic view of the saturator system of FIG. 2 ;

FIG. 5 is a cross-sectional, plan view of the saturator system of FIG. 4along line 5-5;

FIG. 6 is a plan view of a double array saturator system according toanother example of the present invention with access doors in the openposition;

FIG. 7 is a front view of the saturator system of FIG. 6 with theinternal components shown in dashed lines and the access doors in theclosed position;

FIG. 8 is a left side view of the saturator system of FIG. 7 with theinternal components shown in dashed lines;

FIG. 9 is a sample graph explaining the elements of the graphs in thesubsequent Figures.

FIGS. 10-28 show oxygen percent saturation graphs using the saturatorsystem of FIG. 6 .

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS SHOWN IN THE DRAWINGS

An example embodiment of a saturator system 10, a double array saturatorsystem 100, and methods of their use will be discussed. Saturator system10 will first be described.

Saturator System

As shown in FIGS. 1-6 , saturator system 10 generally includes apressure vessel 12, two saturation devices 14, a recirculation system16, and a control system.

Pressure vessel 12 in this example embodiment is generally cylindricalin shape, having a 2.15 meter length with a diameter of 0.61 meters.Pressure vessel 12 comprises an input port 18 situated in the middle ofpressure vessel 12 for receiving a first liquid from an external sourceand an output port 20 for discharging a second liquid that is differentfrom the first liquid, from pressure vessel 12. Output port 20 ispositioned below input port 18, external to pressure vessel 12. Overall,saturator system 10 has a height of about 1.023 meters.

Input port 18 is covered by a shut-off valve (not shown) and downstreamfrom input port 18 is positioned a flow rate sensor 22 for monitoringthe flow of the first liquid into pressure vessel 12. Output port 20 isalso covered by a back-pressure control valve 24 positioned upstream ofoutput port 20 for maintaining fluid pressure within pressure vessel 12.Both input port 18 and output port 20 each have a diameter of about0.203 meters.

Pressure vessel 12 includes a gas inlet 26 for receiving a first gas,and a gas outlet 28 for discharging a second gas, that is different fromthe first gas, from pressure vessel 12. Gas inlet 26 is further in fluidcommunication with gas manifolds 27 situated within pressure vessel 12.Gas manifolds 27 are situated adjacent to and are in fluid communicationwith saturator devices 14. Saturator device 14 is also referred hereinto as a gas infusion device.

Gas outlet 28 in the depicted embodiment includes an air eliminator 30and a pressure relief valve 32, both in fluid communication withpressure vessel 12. Both are adapted to transfer gas from withinpressure vessel 12 to the atmosphere.

Pressure vessel 12 is made of a steel alloy, particularly 316 stainlesssteel, to enable it operate in a salt-water environment. Further,pressure vessel 12 is an ASME-certified pressure vessel, rated for anoperating pressure of 100 psi.

Pressure vessel 12 has two pressure-rated doors 34 with seals. Doors 34cover openings on opposed sides of pressure 12, through which a user mayaccess the internal space within pressure vessel 12 for cleaning andmaintaining of components inside pressure vessel 12.

A mechanical means, or a baffle 36, is further situated within pressurevessel 12. Baffle 36 is adapted to mechanically direct the first liquidfrom input port 18 to saturator devices 14.

Saturator devices 14 are situated within pressure vessel 12 and arepositioned on either side of input port 18, orientated generallyparallel with one another. Each gas infusion device 14 has a first endportion 38, for receiving the first liquid and discharging the secondgas, and an opposed second end portion 40 for receiving the first gasand discharging the second liquid into pressure vessel 12. Each gasinfusion device 14 further has a fibre module array 42 situated betweenthe end portions where fibre module array 42 is made up of a polymercoated microporous fiber material. In the present embodiment, saturatordevices 14 are the saturator or gas infusion device disclosed in U.S.Pat. No. 7,537,200, to Glassford, Oct. 31, 2003.

Recirculation system 16 includes a suction nozzle 44 and two dischargenozzles 46, which are all in fluid communication with pressure vessel12.

Suction nozzle 44 is positioned proximate second end portion 40 of gasinfusion device 14 to draw a portion of liquid into recirculation system16. One discharge nozzle 46 is positioned adjacent each first endportion 38 of each gas infusion device 14 to inject the portion ofliquid back into gas infusion device 14.

Recirculation system 16 includes a pump 48 (see FIGS. 6-8 ) operativelycoupled between suction nozzle 44 and discharge nozzles 46, pump 48being adapted to drive fluid from suction nozzle 44 to discharge nozzles46.

Recirculation system 16 further includes two eductors 50, one eductor 50operatively coupled between each discharge nozzle 46 and itscorresponding gas infusion device 14.

Eductors 50 are made of metal, and in the present embodiment, made of316 stainless steel. In this manner, eductors 50 are adapted to operatein a high-pressure, salt-water environment.

The control system (not shown) is operatively coupled to the flow ratesensor 22 and back-pressure control valve 24. The control system furtherincludes a pressure sensor 52 situated within pressure vessel 12, whichis adapted to measure the fluid pressure within pressure vessel 12, anda regulator (not shown) on gas inlet 26.

Saturator system 10, has mounts 54 fixed to, and extending from,pressure vessel 12. Mounts 54 are mechanical means which allow saturatorsystem 10 to be secured to the ground, a vertical wall and/or to anothersaturator system 10 as described below.

Whereas a specific embodiment of saturator system 10 is herein shown anddescribed, variations are possible. In some examples, pressure vessel 12contains two or more gas inlets 26, two or more air eliminators 30,and/or two or more suction nozzles 44.

In other examples, rather than a two saturator devices 14, pressurevessel 12 may instead house one or more than two saturator devices 14.

As well, instead of the saturator devices being positioned side-by-sideand orientated parallel with one another in an upright position (i.e.linear horizontally) within pressure vessel 12, in other examples, themultiple saturator devices 14 are oriented in one of the following ways:linear vertical, planar horizontal, planar vertical, or arbitrarily.

In other examples, rather than using a single pump, saturator system 10includes two or more pumps as part of its recirculation system 16.

Double Array Saturator System

As shown in FIGS. 6-8 , double array saturator system 100 generallyincludes two saturator systems 10 with a shared recirculation system 16and a common pump 48. Mounts 54 allow one pressure vessel 12 to besecured on top of or above the other pressure vessel 12.

In the shown embodiment, each pressure vessel 12 houses two saturatordevices 14 therein. Each pressure vessel 12 also has its owncorresponding suction nozzle 44 and two discharge nozzles 46, which areall in direct fluid communication with pump 48.

Whereas a specific embodiment of double array saturator system 100 isherein shown and described, variations are possible.

In some examples, each pressure vessel 12 and saturator devices 14 maybe varied as noted above.

In others examples, instead of pressure vessels 12 being positioned oneon top of the other in parallel (i.e. linear vertically), in otherexamples, the multiple pressure vessels 12 are oriented in one of thefollowing ways: linear horizontal, planar horizontal, planar vertical,or arbitrarily.

Double array saturator system 100 may instead have two recirculationsystems 16 (with a pump 48 each), one operatively coupled to eachpressure vessel 12.

Independent Use

Both saturator system 10 and double array saturator system 100 are foruse in conducting a gas exchange with an aqueous-phase liquid inlinewith a tank of water. While the tank is not shown, both saturator system10 and double array saturator system 100 are understood to be coupled tothe tank with piping extending from their input ports 18 and outputports 20. Movement of liquid through the use of systems 10 and 100 areindicated by dashed arrows in the Figures. While not shown in thedrawings, the saturator systems may also be used in a contained, openbody of water.

The first liquid is injected into pressure vessel 12 through input port18, and directed towards first end portion 38 of saturator devices 14 bybaffle 36. The first gas is also injected into vessel 12 through gasinlet 26 and directed to gas manifolds 27, which are adjacent second endportion 40 of each gas infusion device 14.

Simultaneously, a portion of fluid that is proximate second end portion40 of gas infusion device 14 is drawn by pump 48 through suction nozzle44. The portion of fluid is redirected and pumped through dischargenozzles 46 and through eductors 50, which are positioned adjacent firstend portion 38 of saturator devices 14. The force of the redirectedfluid as it travels through eductor 50 draws and drives the first liquidinto first end portion 38 of gas infusion device 14.

In gas infusion device 14, the first liquid and the first gas interactwith the fibre module array, which facilitate a gas exchange between thefirst liquid and first gas as both fluids travels through gas infusiondevice 14. This exchange produces the second liquid and the second gas,which are both discharged from second end portion 40 of gas infusiondevice 14 into the pressure vessel.

While most of the second liquid will be then discharged from pressurevessel 12 through output port 20, some of the second liquid will bedrawn by pump 48 through suction nozzle 44 into recirculation system 16.This liquid is then redirected to first end portion 38 of gas infusiondevice 14 through discharge nozzle 46. This redirected second liquidwill then be pumped through eductor 50 and used to draw the first liquidinto gas infusion device 14 for the gas exchange.

As noted above, both saturator system 10 and double array saturatorsystem 100 are adapted for operation under pressure. In that regard, thecontrol system uses information from flow rate sensor 22 and pressuresensor 52 to maintain the pressure within pressure vessel 12 at apredetermined level. The control system drives back pressure controlvalve 24 and pump 48 in order to maintain sufficient head to drive fluidthrough gas infusion device 14 and to maintain fluid pressure underlow-flow conditions. In the present embodiment, the control systemdrives pump 48 so as to ensure that the pressure in gas infusion device14 is at least 20 psi.

The control system also uses information from flow rate sensor 22 todetermine the amount of the first gas required by each gas infusiondevice 14. The control system controls the regulators connected to gasinlets 26 on pressure vessel 12. The control system may be configured todetect the vibration of pump 48 in order to monitor the pump'smechanical health.

In order to maintain a generally stable total gas pressure, the secondgas is released through air eliminator 30 to the atmosphere. For safety,pressure relief valve 32 may also be used to further release gases frompressure vessel 12 into the atmosphere.

Whereas a specific embodiment of the method is herein shown anddescribed, variations are possible.

In other examples, the control system drives pump 48 may be adapted toensure that the pressure in saturator system 10 is up to 65 psi.

Combined Use

Both saturator system 10 and double array saturator system 100 may beused simultaneously with one or more lift pumps situated within the bodyof water.

The lift pumps are configured to remove carbon dioxide gas from thewater. An example of such a lift pump is disclosed in U.S. 62/607,385.Each lift pump includes a gas input and perforations to enable water toenter the lift pump.

The perforations are situated on a plate for gas to pass through, wherethe plate positioned upstream from a mixing chamber, through which waterenters the lift pump and where the gas forms bubbles which improve gaslift. The perforated plate is made by additive manufacturing withprecise hole dimensions and hole spacing.

As the gas is bubbled into the water through the plate, it reduces thewater density so that the water rises through the lift pump, thusenabling more water to enter through the perforations. As the waterrises, dissolved CO₂ in the water is exchanged with the injected airbased on Henry's Law, such that the partial pressure of dissolved CO₂ inthe water will work to match the partial pressure of CO₂ in the air.

Used together in this manner, the saturator system oxygenates the bodyof water, while the one or more lift pumps remove the dissolved CO₂ andremediates the ammonia to form nitrate.

Such a system may further include one or more oxygen tanks connected tothe saturator system for supplying oxygen to the saturator system, and acompressor coupled to lift pumps to supply ambient air to generate thelift.

Such a system may also have a gas regulator operatively coupled betweenthe oxygen tanks and the saturator system to regulate the flow of gasinto the saturator system, a dissolved oxygen sensor positioned withinthe body of water, a saturator feed pump in fluid communication with thebody of water, adapted to draw and direct water from the body of waterinto the saturator system, and an ammonia sensor positioned within thebody of water.

A control and monitoring system may be in place to communicate with,control and coordinate each of the above components. For example, thecompressor can be activated to engage the lift pumps in response to thedetected concentration of ammonia rising above a maximum level. Thecompressor may then be disengaged to deactivate the lift pumps inresponse to the detected concentration of ammonia falling below aminimum level. In a similar manner, the gas regulator and the saturatorfeed pump may be activated and controlled in response to the detectedconcentration of oxygen falling below a minimum level. The gas regulatorand the saturator feed pump may also be deactivated accordingly.

Whereas a specific embodiment of the method is herein shown anddescribed, variations are possible.

Testing

The following tests were conducted. The first gas used was oxygen andthe first liquid was oxygen-poor and carbon dioxide-rich saltwater oroxygen-poor and carbon dioxide-rich freshwater.

Requirements

-   -   Tank of water    -   Discharge Pipes    -   Suction pipe    -   Recirculation pump    -   Pressure control valve    -   Variable speed pump(s)    -   Oxygen source    -   Measuring equipment (Oxygen, total gas pressure, temperature,        Salinity, pressure, Oxygen flow, water flow)

The tests were set up by connecting the suction and discharge pipes,respectively, to the inlet port and the outlet port of the saturatorsystem, the other ends of the pipes were placed in the tank of water, onopposite sides of the tank to ensure good circulation of oxygenatedwater. The pressure control valve is positioned between the saturatorsystem and the discharge pipe to the tank.

Background measurements of the water tank were taken, noting salinity,temperature, total gas pressure and oxygen readings.

A small amount of oxygen is fed to the unit to keep the fibers of thesaturator devices clear of water.

The variable speed pumps are then turned on to allow water from the tankto flow into and fill the pressure vessel and the pipes.

The pressure control valve is partially closed to increase the pressurewithin the pressure vessel to the desired level.

By adjusting the water flow and pressure within the pressure vessel, thedesired predetermined parameters are eventually achieved. The parametersfor the trials are set out in Table 1 below.

The recirculation pump is then turned on and increased until there is atleast 30 PSI differential between the recirculation pump pressure andthe unit pressure.

The oxygen is turned on at the desired level.

The saturator system was then run for the predetermined desired time.

The saturator system is then shutdown in reverse order, i.e. first theoxygen is turned off, then the recirculation pump, and then pressure.

Readings are taken for oxygen, temperature, and total gas pressure andcompared to the previous values. Previous values are those of water atsea level, that being 100% oxygen saturation, 15 Degrees C., at 760 mmHg(100% total gas pressure). If the tank did not mix properly, severallocations will have to be measured to get a full profile on the tank.

Based on these comparisons, it was determined how much oxygen was addedto the water and how much other gas was removed.

A number of tests were run according to the following rationale, and theresults illustrated in the noted Figures.

FIG. 9 is a sample graph explaining the elements of the graphs in thesubsequent Figures.

-   -   A: Point at which the pump was turned on    -   B: Trial name indicating salinity, pressure in pounds per square        inch, water flow in liters per minute and Oxygen flow in liters        per minute (corrected for pressure)    -   C: Calculated grams of oxygen infused per minute    -   D: The theoretical value that should be obtained based on our        internal models    -   E: Actual Oxygen percent saturation readings    -   F: Time during which Oxygen was added

FIGS. 10-28 show percent saturation data using the saturator system ofFIG. 6 .

-   -   Trial 1: This test was preformed as a first attempt to replicate        the most basic function of the unit in fresh water (FW) to see        if it compared favorably to the models. See FIG. 10 .    -   Trial 2: This test was preformed as an attempt to replicate the        most basic function of the unit in fresh water at an known        operating pressure for smaller units. See FIG. 11 .    -   Trial 3a: This test was preformed to see if there was an issue        with the right array. See FIG. 12 .    -   Trial 3b: This test was preformed to see if there was an issue        with the left array. See FIG. 13 .    -   Trial 4: This test was preformed at an increased differential        pressure in the arrays and an account taken for the volume of        piping in the experiment. See FIG. 14 .    -   Salt water (SW) trial 1: This test was preformed as a first        attempt to replicate the most basic function of the unit in salt        water at an increased differential to see if it compared        favorably to the models. See FIG. 15 .    -   SW trials 2, 3, 5, 7, 8, 9, 10, and 11: These trials were        performed to push the limits of the device and see how accurate        our current modeling system reflected reality in salt water. See        FIGS. 16-23 .    -   FW trials 1-5: These trials were performed to push the limits of        the device and see how accurate our current modeling system        reflected reality in fresh water. See FIGS. 24-28 .

The outcome for the salt water and fresh water trials (corresponding toFIGS. 15-27 ) are also summarized in Table 1 below.

The tests show that levels of oxygen could be infused at levels notpreviously possible with conventional equipment while keeping the totalgas pressure (TGP) relatively unchanged. For example, in Saltwater trial11, the saturator system was operated at 65 internal psi, with waterflow at 8000 L/min and oxygen flow at 245 L/min. While dissolved oxygenlevels reached 447 percent saturation, the overall total gas pressurechange was only 6.5 percent.

In comparison, existing saturator devices can only dissolve oxygen inwater to reach 300 percent saturation, while the overall total gaspressure change is usually 140 percent, which is lethal to aquatic life.

As such, an advantage of the use of the present saturator system 10and/or double array saturator system 100 is that the oxygen could beinfused into the water at nearly ten times the amount of oxygen thatwould be infused by using the prior art saturator device while the totalgas pressure in the liquid remains relatively unchanged.

Another advantage of the present saturator system is that it enables gasto be infused into an aqueous liquid under pressure with a high flowrate without increasing or significantly increasing the total gaspressure in the liquid.

The invention should be understood to be limited only by theaccompanying claims, purposively construed.

TABLE 1 Water Back Recirc Oxygen Oxygen Trial Temp Flow PressureRotameter Oxygen Pressure Target O2 Delivered Delivered % TGP EfficiencyFinal # FW/SW (C.) (LPM) (psi) (LPM) (LPM) (psi) (gm/min) (gm/min) (LPM)Change % % DO Apr. 16-19, 2018 1 SW 19.17 3000 17.5 21 60 47.5 64.6 6746.8 6 78 208 2 SW 17.34 3200 21.5 22.8 70 51.5 82.6 87.8 61.4 3.25 87.7231 3 SW 17.08 3400 26 24.6 80 56 97.1 102 71.3 4.3 89.1 240 5 SW 10.243800 30.3 29.3 100 61 124.5 130.2 91.1 4.5 91.3 253 7 SW 17.28 400036.85 31.5 115 67 140.4 133.3 93.2 3.4 81.1 268 8 SW 16.91 4000 43.2533.5 130 74 161.7 154.6 108.1 2.85 83.2 294 9 SW 11.44 4500 52 38.5 16085 208.7 186.4 130.4 3.05 81.5 307 May 2-4, 2018 1 FW 11.3 4000 30.3517.6 60 90 66 68 47.6 6 79.3 173 2 FW 11.6 6000 34.7 20 70 92 90 99 69.23.5 98.9 191 3 FW 12.1 8000 45.5 22 85 100 113.1 112.3 78.5 4.5 98.1209.4 4 FW 12.5 8000 45.1 31.8 125 100 125 152 106.3 9 85.1 244 10 SW19.1 6000 52 45.7 190 90 210 225 157.4 7 82.8 354 11 SW 19.2 8000 6553.9 245 105 265 295 206.3 6.5 91.7 447

The invention claimed is:
 1. An inline saturator system for gas exchangewith an aqueous-phase liquid, the system comprising: a pressure vesselconfigured to receive a first liquid and a first gas from externalsources, and to discharge a second liquid and a second gas from thepressure vessel; a gas infusion device situated within the pressurevessel, the gas infusion device configured to receive the first liquidand first gas, to facilitate gas exchange between the first liquid andfirst gas, producing the second liquid and the second gas, and todischarge the second liquid and second gas into the pressure vessel; anda recirculation system configured to redirect a portion of liquid withinthe pressure vessel back into the gas infusion device; wherein injectionof the redirected liquid into the gas infusion device forces the firstliquid into the gas infusion device for the gas exchange.
 2. Thesaturator system of claim 1, wherein the recirculation system furthercomprises an eductor fluidly coupled to the gas infusion device, theinjection of the redirected liquid through the eductor drawing the firstliquid through the eductor into the gas infusion device.
 3. Thesaturator system of claim 1, wherein the pressure vessel has: an inputport for receiving the first liquid, an output port for discharging thesecond liquid from the pressure vessel, a gas inlet for receiving thefirst gas, and a gas outlet for discharging the second gas from thepressure vessel.
 4. The saturator system of claim 1, wherein the gasinfusion device has: a first portion for receiving the first liquid anddischarging the second gas, an opposed second portion for receiving thefirst gas and discharging the second liquid into the pressure vessel,and a fibre module array situated therebetween for facilitating the gasexchange between the first liquid and the first gas to produce thesecond liquid and the second gas.
 5. The saturator system of claim 4,further comprising a baffle: situated within the pressure vessel, andconfigured to direct the first liquid from the input port of thepressure vessel to the first portion of the gas infusion device.
 6. Thesaturator system of claim 5, wherein the recirculation system comprises:a suction nozzle and a discharge nozzle, both in fluid communicationwith the pressure vessel, and a pump operatively coupled between thesuction nozzle and the discharge nozzle, the pump for driving fluid fromthe suction nozzle to the discharge nozzle.
 7. The saturator system ofclaim 6, wherein the suction nozzle is positioned proximate the secondportion of the gas infusion device to draw a portion of liquid into therecirculation system, and the discharge nozzle is positioned adjacentthe first portion of the gas infusion device to inject the portion ofliquid into the gas infusion device.
 8. The saturator system of claim 7,wherein the pressure vessel comprises a steel alloy.
 9. The saturatorsystem of claim 7, wherein the pressure vessel has one or morepressure-rated doors with seals to allow for cleaning and maintaining ofcomponents inside the pressure vessel.
 10. The saturator system of claim9, further comprising a back-pressure control valve positioned upstreamof the output port for maintaining fluid pressure within the pressurevessel.
 11. The saturator system of claim 10, wherein the pump of therecirculation system is configured to generate a pressure of at least 20psi through the gas infusion device.
 12. The saturator system of claim11, further comprising a second gas infusion device positioned withinthe pressure vessel.
 13. The saturator system of claim 12, wherein therecirculation system includes a second discharge nozzle positionedadjacent the second gas infusion device to inject liquid into the secondgas infusion device.
 14. The saturator system of claim 13, wherein therecirculation system includes a second eductor coupled between thesecond discharge nozzle and the second gas infusion device.
 15. Thesaturator system of claim 14, wherein the recirculation system includesa second pump in fluid communication with the second discharge nozzle.16. The saturator system of claim 14, further comprising: a secondpressure vessel configured to receive the first liquid and the first gasfrom external sources, and to discharge the second liquid and the secondgas from the second pressure vessel; a third gas infusion devicesituated within the second pressure vessel, the third gas infusiondevice configured to receive the first liquid and first gas, tofacilitate gas exchange between the first liquid and first gas,producing the second liquid and the second gas, and to discharge thesecond liquid and second gas into the second pressure vessel; and therecirculation system further configured to redirect a portion of liquidwithin the second pressure vessel back into the third gas infusiondevice; wherein injection of the redirected liquid into the third gasinfusion device forces the first liquid in the second pressure vesselinto the third gas infusion device for the gas exchange.
 17. A methodfor gas exchange with an aqueous-phase liquid, the method comprising:injecting a first liquid and a first gas into a pressure vessel;directing the first liquid and the first gas through a gas infusiondevice situated within the pressure vessel, the gas infusion deviceconfigured to facilitate gas exchange between the first liquid and thefirst gas, producing a second liquid and a second gas; redirecting aportion of the second liquid back into the gas infusion device; anddischarging the remaining second liquid out of the pressure vessel;wherein the redirection of the second liquid into the gas infusiondevice draws the first liquid into the gas infusion device for the gasexchange.
 18. The method of claim 17, wherein the redirecting includespumping the portion of second liquid into the gas infusion devicethrough an eductor, thereby drawing the first liquid within the pressurevessel through the eductor into the gas infusion device.
 19. The methodof claim 18, further comprising maintaining the pressure within the gasinfusion device at a predetermined level.
 20. The method of claim 19,wherein the predetermined pressure maintained within the gas infusiondevice is at least 20 psi.